Study On The Response Of The Nonresonant Plasma Wave THz Device

Recently with the increasing use of electromagnetic radiation, THz technology has been gained more and more researchers' attention because of its specificity. The pursuit of higher performance of THz sources and THz detectors, which are important in THz technology, has never been stopped. The semiconductor devices are preferred to be the core of THz devices for the sake of mature manufacturing process and easy integration. All kinds of semiconductor THz devices based on different mechanisms are constantly developed. Because of its unique physical principles, a plasma wave device can be used as a THz radiation source or a THz radiation detector at room temperature.The conclusion that the electrons in the channel of a plasma wave device can be compared to plasmas is drawn in this paper through the introductions of the two plasma wave devices(HEMT and MOSFET) and plasmas. The behaviors of plasmas are usually described by a fluid description. Based on hydrodynamic equations, the causes and boundary conditions of the generation of plasma waves in a plasma wave device are discussed in this paper. And the physical meaning of the plasma waves excited in a plasma wave device is discussed.Then the potential of the plasma wave device to be a THz detector are described in this paper. A mathematical model for describing the response of a nonresonant plasma wave device is obtained based on the hydrodynamic equations. This mathematical model describes the relationship between the response of the detector in the gradual channel approximation and the gate voltage as well as the relationship between the response of the detector in the gradual channel approximation and the drain current. Through the analysis of the model, the conclusion is drawn that the model is invalid when the gate voltage is close to or below the threshold. By modifying the relationship between the electronic density in the channel and the gate voltage when the gate voltage is close to or below the threshold, a new mathematical model for describing the relationship between the device response and the gate voltage is obtained.Through the MATLAB software, the theoretical model and the actual measurement data are compared to verify the correctness of the model. Then the error between the theoretical model and the actual measurement data is analyzed. In this paper, the contributions of the leakage current, the electron mobility and the actual circuit to the error are briefly analyzed. Then the relationships between the response of the device and the parameters of k',? and temperature are discussed. And the range of applicability of the response model is obtained by calculation and analysis. Finally, some problems in the model as well as the effects of these problems on the response of the device are described. Also the future development of the plasma wave device and the requirements for the structure of the device are described.